Use "from . import" for relative imports

Will fail in python3 otherwise.

Signed-off-by: Sebastian Spaeth <Sebastian@SSpaeth.de>

offlineimap/folder/Gmail.py

@@ -18,7 +18,7 @@
 
 """Folder implementation to support features of the Gmail IMAP server.
 """
-from IMAP import IMAPFolder
+from .IMAP import IMAPFolder
 
 class GmailFolder(IMAPFolder):
     """Folder implementation to support features of the Gmail IMAP server.

offlineimap/folder/IMAP.py

@@ -21,7 +21,7 @@ import binascii
 import re
 import time
 from sys import exc_info
-from Base import BaseFolder
+from .Base import BaseFolder
 from offlineimap import imaputil, imaplibutil, OfflineImapError
 from offlineimap.imaplib2 import MonthNames
 

offlineimap/folder/LocalStatus.py

@@ -15,7 +15,7 @@
 #    along with this program; if not, write to the Free Software
 #    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
 
-from Base import BaseFolder
+from .Base import BaseFolder
 import os
 import threading
 

offlineimap/folder/LocalStatusSQLite.py

@@ -17,7 +17,7 @@
 import os.path
 import re
 from threading import Lock
-from LocalStatus import LocalStatusFolder
+from .LocalStatus import LocalStatusFolder
 try:
     import sqlite3 as sqlite
 except:

offlineimap/folder/Maildir.py

@@ -19,7 +19,7 @@ import socket
 import time
 import re
 import os
-from Base import BaseFolder
+from .Base import BaseFolder
 from threading import Lock
 
 try:

offlineimap/folder/UIDMaps.py

@@ -15,7 +15,7 @@
 #    along with this program; if not, write to the Free Software
 #    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
 from threading import Lock
-from IMAP import IMAPFolder
+from .IMAP import IMAPFolder
 import os.path
 
 class MappedIMAPFolder(IMAPFolder):

offlineimap/folder/__init__.py

@@ -1,2 +1,2 @@
-import Base, Gmail, IMAP, Maildir, LocalStatus
+from . import Base, Gmail, IMAP, Maildir, LocalStatus